Alternating hardmasks for tight-pitch line formation

Abstract

A method for forming fins includes forming a three-color hardmask fin pattern on a fin base layer. The three-color hardmask fin pattern includes hardmask fins of three mutually selectively etchable compositions. Some of the fins of the first color are etched away with a selective etch that does not remove fins of a second color or a third color and that leaves at least one fin of the first color behind. The fins of the second color are etched away. Fins are etched into the fin base layer by anisotropically etching around remaining fins of the first color and fins of the third color.

What is claimed is: 
     
       1. A method of manufacturing a semiconductor integrated circuit comprising:
 providing a plurality of hardmask fins above a substrate, wherein: 
 the plurality of hardmask fins comprises first hardmask fins and second hardmask fins, each of the first and second hardmask fins comprising a first-color material; 
 the plurality of hardmask fins alternate between a hardmask fin of the first hardmask fins and a hardmask fin of the second hardmask fins; and 
 each of the first hardmask fins has a greater height than each of the second hardmask fins; 
 forming a layer of a second-color material between the alternating first and second hardmask fins and over the second hardmask fins, such that an upper surface of each of the first hardmask fins is exposed and an upper surface of each of the second hardmask fins is covered; 
 removing the first hardmask fins to provide gaps between regions of the second-color material layer; and 
 forming third hardmask fins comprising a third-color material in the gaps. 
 
     
     
       2. The method of  claim 1 , further comprising:
 etching, using a mask, to selectively remove one or more second hardmask fins. 
 
     
     
       3. The method of  claim 2 , further comprising:
 removing the second-color material layer; and 
 transferring a resultant pattern of second and third hardmask fins to an underlying layer. 
 
     
     
       4. The method of  claim 2 , wherein using the mask comprises using a mask having an opening that exposes at least one upper surface of a third hardmask fin. 
     
     
       5. The method of  claim 4 , wherein using the mask further comprises having an opening that exposes at least two upper surfaces of third hardmask fins. 
     
     
       6. The method of  claim 1 , further comprising:
 etching, using a mask, to selectively remove one or more third hardmask fins. 
 
     
     
       7. The method of  claim 6 , further comprising:
 removing the second-color material layer; and 
 transferring a resultant pattern of second and third hardmask fins to an underlying layer. 
 
     
     
       8. The method of  claim 6 , wherein using the mask further comprises using a mask having an opening that exposes at least one upper surface of a second hardmask fin. 
     
     
       9. The method of  claim 8 , wherein using the mask further comprises having an opening that exposes at least two upper surfaces of second hardmask fins. 
     
     
       10. The method of  claim 1 , further comprising:
 etching, using a first mask, to selectively remove one or more second hardmask fins; and 
 etching, using a second mask, to selectively remove one or more third hardmask fins. 
 
     
     
       11. The method of  claim 10 , further comprising:
 removing the second-color material layer; and 
 transferring a resultant pattern of second and third hardmask fins to an underlying layer. 
 
     
     
       12. The method of  claim 1 , wherein a pitch between adjacent second hardmask fins is substantially the same as a pitch between adjacent third hardmask fins. 
     
     
       13. The method of  claim 1 , wherein a pitch between adjacent second and third hardmask fins is approximately one-half a pitch between adjacent second hardmask fins. 
     
     
       14. The method of  claim 1 , wherein a pitch between adjacent second and third hardmask fins is approximately 20 nm. 
     
     
       15. The method of  claim 1 , wherein the second-color material layer comprises carbon. 
     
     
       16. The method of  claim 1 , wherein upper surfaces of the first hardmask fins comprise a first capping material, upper surfaces of the second hardmask fins comprise a second capping material, and wherein the first and second capping materials are different. 
     
     
       17. The method of  claim 1 , wherein the first and second hardmask fins each comprise a lower portion having an upper surface comprising the first-color material and an upper portion comprising one or more capping materials, and wherein the upper portion of each of the first hardmask fins has a greater height than the upper portion of each of the second hardmask fins. 
     
     
       18. The method of  claim 17 , wherein the lower portions of each of the first and second hardmask fins have approximately the same height. 
     
     
       19. The method of  claim 17 , wherein the upper portions of the first hardmask fins comprise at least a first capping material and a second capping material, and wherein the upper portions of the second hardmask fins comprise the first capping material but not the second capping material. 
     
     
       20. The method of  claim 1 , wherein the second-color material layer comprises a spin-on material.